Bubble cap assemblies and bubble towers embodying the same



March 27, 1962 A. c. ELD ETAL BUBBLE CAP ASSEMBLIES AND BUBBLE TOWERS EMBODYING THE SAME Filed May 5, 1958 3,027,145 BUBBLE CAP ASSEMBLEES AND BUBBLE TQWERS EMBQDYKNG THE SAME Aksel C. Eld, Pittsburgh, and Wiliiam R. Lehrian,

Verona, Pa., assignors to Gulf Oil Corporation, Pittsburgh, Pa, a corporatiun of Pennsyivania Filed May 5, 1958, Ser. No. 732,959 4 Claims. (Cl. 261-414) The present invention pertains to new and useful improvements in bubble towers, and more particularly relates to bubble cap assemblies of the type wherein the vapor flow therethrough is valved.

Broadly, the present invention involves a bubble cap assembly comprising an upstanding chimney adapted to be secured to a tray deck about an aperture in the tray deck, with the upper end of the chimney constituting a valve seat. A plate valve rests on the valve seat at the upper end of the chimney, with guide means provided for positioning the plate valve over the chimney and also for guiding free vertical movement of the plate valve between a position resting on the valve seat and a position spaced thereabove. Such guide means comprises a spider comprised of a plurality of angularly spaced, centrally connected, radially and horizontally extending vanes spaced above the chimney, with each of the vanes having a downturned outer end portion that is secured to the chimney. The downturned end portions of the spider vanes are horizontally spaced from the plate valve to allow a limited horizontal freedom of movement for the plate valve. A bubble cap is carried by the spider having sides extending to a position below the upper end of the chimney.

The invention also involves the plate valves of various bubble cap assemblies of a single tray deck having different weights depending upon the relative distances of the bubble cap assemblies between the seal weir and the overflow weir associated with such tray deck. In general, the weights of the various plate valves are adjusted so that a uniform vapor flow passes through each of the bubble cap assemblies in spite of the surface gradient of the liquid supported on the tray deck between the seal weir and the overflow weir.

The invention also involves either as an alternative for or as a supplement to the various weightings of the plate valves the provision of the chimneys of the various bubble cap assemblies being of dilfering heights so as to tend to equalize the liquid heads on the various plate valves arising from the liquid gradient.

The invention will be fully comprehended in the light of the following description of a preferred embodiment of the invention illustrated in the accompanying drawings, wherein:

FIGURE 1 is a central vertical sectional view of a portion of a bubble tower with parts broken away, with all save one of the bubble cap assemblies being shown in side elevation;

FIGURE 2 is a reduced horizontal sectional view taken upon the plane of the section line IIII of FIGURE 1;

FIGURE 3 is a top plan view of a bubble cap assembly according to the invention, portions of the same being removed to illustrate internal structure, together with dashed lines being employed to show the location of hidden structural parts; and

FIGURE 4 is a vertical sectional view taken upon the plane of the section line IVIV of FIGURE 3.

3,Z7,l45 Patented Mar. 2?, 1962 ice Referring to FIGURES 1 and 2, the reference numeral 10 designates the upstanding tubular shell of a bubble tower in which there are shown two vertically spaced, horizontal bubble tray decks 12 and 14. The tray decks 12 and 14 are respectively provided with upstanding seal weirs 16 and 18, and upstanding overflow weirs 20 and 22. The overflow weirs 2t} and 22 are respectively provided with downflow aprons 24 and 26 that extend down into the seal weir of the tray deck next therelbelow, as illustrated particularly in connection with downfiow apron 24 and seal weir 18, it being noted that a downfiow apron 28 extends down into the seal weir 16 from the tray deck (not shown) next above the tray deck 12. The structure thus far described is entirely conventional and will be well understood by those skilled in the art.

Each of the tray decks 12 and 14 is provided with a plurality of bubble cap assemblies, and since the number and spacing of the bubble cap assemblies associated with the tray deck 14 is the same as for the tray deck 12, only the bubble cap assemblies associated with the tray deck 12 will be described in detail. The bubble cap assemblies associated with tray deck 12 are indicated generally by the reference numeral 36 and are arranged in spaced relationship between the seal weir 16 and the overflow weir 26, as best shown in FIGURE 2.

Attention is now directed to FIGURES 3 and 4 for an understanding of the structure of an individual bubble cap assembly 3%). At each location of a bubble cap assembly 30 on the tray deck 12, there is provided a circular aperture, and the peripheral edge of the tray deck 12 is upturned about such aperture, as indicated at 32. A hollow, circular cylindrical chimney 34 extends through the aperture in engagement with the peripheral upturned edge 32 of the tray deck 12, with the lower extremity of the chimney 34 being outturned so as to bear against the underside of the tray deck 12, as indicated at 36. The chimney 34 is secured to the tray deck 12 in the described relationship in any suitable manner, such as by spot welding, so as to afford a vapor-tight connection therebetween.

The upper edge 38 of the chimney 34 constitutes a valve seat for a circular plate valve 4t) of larger diameter than the chimney 34. Means is provided for positioning the plate valve 44 above the chimney 34 and also for guiding free vertical movement of the plate valve 40 while allowing a limited amount of horizontal freedom for the plate valve 40. Such means comprises a spider construction consisting of a plurality of angularly spaced, centrally connected, radially and horizontally extending vanes 42, 44, 46, and 48 (see FIGURE 3), which can be conveniently constructed of three pieces of sheet or thin plate material by welding or brazing the vanes 46 and 48 to a single piece of material constituting the vanes 42 and 44, as indicated at St). Each of the vanes 42, 44, 46, and 48 is essentially U-shaped so as to constitute spaced upper and lower legs, such spaced upper and lower legs for the vanes 42, 44, and 43 being respectively designated at 52 and 54, 56 and 53, and 6t) and 62 in FIGURE 4. The outer extremities of the upper and lower legs of each of the vanes 42, 44, 46, and 43 are connected by web portions 64, d6, 68, and 70, respectively, the adjacent edges of such Web portions being spaced a greater distance from the juncture of the vanes 42, 44, 46, and 43 than the radius of the plate valve 46, as shown. The upper edge of the chimney 34 is provided with slots, such as those indicated at 72 vand 74, in which the lower legs of the vanes 42., 44., 46, and 48 are received. Positioning of the spider construction relative to the chimney 34 is facilitated by the lower legs each having an upwardly and outwardly tapered bottom edge portion, such as that indicated at 76 in connection with the lower leg 54 of the vane 42. The vanes are brazed or otherwise suitably secured to the chimney 34-, as indicated at 78 in connection with the lower leg 62 of the vane 48.

It will be noted that the upper edges of the lower legs of the vanes 42, 44, 46, and 4.8 are spaced below the upper edge of the chimney 34. Though such spacing is not essential, it is preferred, as such spacing will prevent any possible interference with the proper seating of the valve plate 4-0 upon the valve seat constituted by the upper edge of the chimney 34. If deemed necessary, the portions of the slots in the chimney 34 in which the vanes are received above the lower legs of the vanes can be filled with brazing material or the like in order to prevent vapor leakage.

The single sheet of material of which the vanes 42 and 443 are constructed is provided with a central upstanding lip or protrusion 79 at the juncture of the upper legs 52 and 56 having a central vertical slot 89 therein for a purpose presently to be described.

An inverted, cup-shaped bubble cap 82 is positioned over the spider construction with the same engaging the upper edges of the upper legs of the vanes 42, 44, 46, and 48, as shown, with the lip or protrusion '79 being received through a complementary slot in the top of the bubble cap 32;. The bubble cap 82 is retained in assembled relation on the spider and the chimney 34 by means of a wedge key 84- extending through the slot 86 in the lip or protrusion 79 and bearing against the top of the bubble cap 82.

The bubble cap 82 has sides 86 that extend to a position substantially below the top of the chimney 34 and terminate in spaced relation above the tray deck 12. The bubble cap 82 is circular and the depending sides 86 thereof are provided with a plurality of circumferentially spaced, somewhat triangular slots 88 that are disposed entirely below the top of the chimney 34. The upper edge of the chimney 34 is at least as high as the upper edge of the overflow weir 2t and can extend somewhat higher, while the upper extremities of the slots 88 can be at, but are preferably spaced below the upper extremity of the overflow weir 2% Referring again to FIGURE 2 in the drawings, it will be apparent that the relative distances of the bubble cap assemblies to the seal weir 16 and the overflow weir 20 vary across the tray deck 12. Ordinarily, a surface gradient will exist with respect to liquid retained on the tray deck 12, the liquid having its maximum height adjacent the seal Weir 16 and its minimum height adjacent the overflow weir 2t this being true even when the seal weir 16 has a lesser height than the overflow weir 20. For a reason to become apparent during the ensuing description of the operation of the illustrated embodiment of the invention, the plate valves 40 for the various bubble cap assemblies 39 have differing weights, depending upon their relative spacing with respect to the weirs 16 and 28, the plate valves 40 of the assemblies 30 next the overflow weir 20 having relatively greater weights. Also (see FIGURE 1) it will be noted that proceeding from the weir 20 towards the weir 16 that the bubble caps are progressively taller. This variation in heights is due solely to variation of the chimney heights. In general, the chimneys of the various bubble cap assemblies are more or less proportional to the depth of the liquid in the immediate region during operation.

The operation of the apparatus described above will be readily understood. During operation of the apparatus, liquid travels downwardly through the downfiow apron 28, over the seal weir 16, across the tray deck 12, about the bubble cap assemblies 30, over the overflow weir 20, down the downfiow apron 24, over the seal weir 13, across the tray deck 14, over the outlet Weir 22, and down the downflow apron 26. While liquid passes downwardly, in the described manner, vapor passes upwardly through the shell 10 and successively through the bubble 5 cap assemblies 3t? of the tray decks l4 and 12, with the bubble cap assemblies 30 affording an intimate contact between the ascending vapor and the liquid passing over the tray decks 14 and 12.

The bubble cap assemblies 39 afford an intimate vapor liquid contact uniformly over the entire area of the tray decks 12 and 14 because of the fine subdivision of the vapor streams passing therethrough and the introduction into the liquid as small bubbles, this being accomplished substantially uniformly throughout the area of the tray 15 decks because of the action of the plate valve 49 in controlling the upward vapor flow through the individual bubble cap assemblies 30. The control effected by the plate valve 49 in causing a uniformity of vapor distribution as among the various bubble cap assemblies 30 on each tray deck stems from the fact that the vapor must in passing through a bubble cap assembly 30 raise the plate valve 4h from its seat to a position such as that indicated in dashed outline at 9i in FIGURE 4, with the weight of the plate valve 40 constituting at least a substantial part of the total resistance to vapor flow through the bubble cap assembly and into the surrounding liquid, so that variations in liquid level height result in minor differences between the vapor flow through bubble cap assemblies 30 of the same tray deck. Differences of 30 vapor flow as between bubble cap assemblies 30 of the same tray deck are further minimized by utilizing plate valves 45) of diflering weights so as to afiord differing resistances to vapor flow. In general, the plate valves 40 have weights diifering by amounts suflicient to compensate substantially for the different liquid heads surrounding their respective bubble cap assemblies where such differing liquid heads are a consequence of the surface graclient of liquids passing over the tray deck. Accordingly, since the surface gradient is such that the liquid depth is greatest adjacent the seal Weir and least adjacent the overflow weir, the plate valves 40 of the bubble cap assemblies 30 next to the seal weir 16 have the least weight, while the plate valves 40 of the bubble cap assemblies 30 next to the overflow weir 20 have the maximum weight, with the plate valves 44) of bubble cap assemblies 30 disposed in between having intermediate weights.

The variations in the weights of the plate valves 40 between maximum and minimum weights can be as much as about four ounces when the chimney diameter is four inches as the variation in liquid depth can be as much as one inch across a tower, though lesser weight variation will normally sufice.

While variation in plate valve weights is ordinarily preferred as a control in equalizing vapor flow rates, such control can be modified by varying the chimney heights 1n the same sense as the variations in their respective plate valve weights. In other words, the weight of a plate valve can be increased when the height of its associated chimney is increased. It will be appreciated that in some applications, the variation in plate valve weights can be dispensed with entirely upon suitable selection of chimney heights; however, since plate valve weights can be more readily changed than chimney heights, it is preferred that uniformity of vapor flow be controlled at least in part by the weights of the plate valves.

With the above-described variation in weight of the plate valves 40 and/or of the chimney 34 heights, the total resistance to vapor flow through each one of the bubble cap assemblies 30 irrespective of its relative locationwith respect to the weirs will be essentially equal,

and with the result that vapor distribution is substantially uniform throughout each set of bubble cap assemblies 30 oneach tray deck.

One of the principal advantages of the bubble cap assemblies 30 is that the valving of vapor is controlled with the plate valves being alforded a freedom of movement both horizontally and vertically such as to be essentially entirely free of becoming jammed as can occur in the use of structures heretofore proposed for valving vapor; this being especially important when the liquids and vapors being processed contain impurities or are of such a character as to tend to polymerize, etc. and form hard or gummy deposits. The freedom of movement afforded the plate valve 40 is such as to serve a cleaning function both of itself and of the surfaces with which it comes in contact during its loosely constrained motions. It will be obvious that it is of substantial importance that the plate valve 40 not be stuck or jammed during operation of the apparatus inasmuch as such sticking or jamming will result in poor vapor distribution and can also possibly result in liquid dumping through the chimney 34 when the surface gradient of liquid is such that the liquid level is above the top of the chimney 34.

It will be appreciated by those skilled in the art that the illustrated embodiment of the invention is particularly well suited for fractionation of petroleum fractions, particularly those fractions containing unsaturates susceptible to polymerization and gum formation, as well as those which may contain solid impurities such as finely divided catalyst particles; however, the apparatus can also be used with comparable benefits in other vapor-liquid contacting processes such as in absorption, distillation, rectification, dephlegmation, dehydration, and the like.

It will be understood that the bubble cap assemblies of the illustrated and described preferred embodiment can be utilized in vapor-liquid contacting arrangements other that the particular form illustrated in FIGURE 1, such as the conventional twin-flow fractionation or bubble tower construction. These and other modifications of the described and illustrated embodiment of the invention will be readily apparent to those skilled in the art, and accordingly attention should be directed to the appended claims in order to ascertain the actual scope of the invention.

We claim:

1. A bubble cap assembly comprising an upstanding chimney, the lower end of which is adapted to be secured to a tray deck about an aperture in the tray deck, a plate valve resting on the upper end of the chimney, with the upper end of the chimney constituting a valve seat for the plate valve, said plate valve being provided with guide means for positioning the plate valve over the chimney and also for guiding free vertical movement of the plate valve between a position resting on the valve seat and a position spaced thereabove, said guide means comprising a spider comprised of a plurality of angularly spaced, centrally connected, radially and horizontally extending vanes spaced above the chimney, each of said vanes having a downturned end portion that is secured to the chimney adjacent to the upper end of the latter, said downturned end portions of the spider vanes being horizontally spaced from the plate valve to allow a limited horizontal freedom of movement for the plate valve, and a bubble cap carried by the spider having sides extending to a position below the upper end of the chimney, and said sides of said bubble cap having openings therein, said openings being positioned circumferentially around said bubble cap at a height lower than the upper end of said chimney.

2. A bubble cap assembly comprising an upstanding circular chimney, the lower end of which is adapted to be secured to a tray deck about an aperture in the tray deck, a circular plate valve of greater diameter than the chimney resting on the upper end of the chimney, with the upper end of the chimney constituting a valve seat for the plate valve, said plate valve being provided with guide means for positioning the plate valve over the chimney and also for guiding free vertical movement of the plate valve between a position resting on the valve seat and a position spaced thereabove, said guide means comprising a spider comprised of a plurality of angularly spaced, centrally connected, radially and horizontally extending vanes spaced above the chimney, each of said vanes having a downturned end portion that is secured to the chimney adjacent to the upper end of the latter, said downturned end portions of the spider vanes being horizontally spaced from the plate valve to allow a limited horizontal freedom of movement for the plate valve, a bubble cap covering the chimney in spaced relation thereto and having sides extending to a position below the upper end of the chimney, said spider vanes having upper edges in supporting engagement with the bubble cap, and said sides of said bubble cap having openings therein, said openings being positioned circumferentially around said bubble cap at a height lower than the upper end of said chimney.

3. A bubble cap assembly comprising an upstanding circular chimney, the lower end of which is adapted to be secured to a tray deck about an aperture in the tray deck, a circular plate valve of greater diameter than the chimney resting on the upper end of the chimney, with the upper end of the chimney constituting a valve seat for the plate valve, said plate valve being provided with guide means for positioning the plate valve over the chimney and also for guiding free vertical movement of the plate valve between a position resting on the valve seat and a position spaced thereabove, said guide means com prising a spider comprised of a plurality of angularly spaced, centrally connected, radially and horizontally extending vanes, each of said vanes being a vertical plate and essentially U-shaped in the vertical plane so as to define horizontal, vertically spaced upper and lower legs which are connected by a vertical web at the radial extremity of the vane, whereby the vanes of the spider are jointly conformable to a cylindrical space having a height equal to the spacing of the legs of the vanes and a diameter in excess of that of the plate valve, said chimney having a plurality of slots in the upper end thereof, with the lower legs of the spider vanes being positioned in said slots, and a bubble cap carried by the spider having sides extending to a position below the upper end of the chimney.

4. In a bubble tower comprising an upstanding shell within which is disposed a plurality of vertically spaced bubble trays, each of said bubble trays comprising a tray deck provided with an upstanding overflow weir and a depending downflow apron therefor, each of said tray decks also being provided with a seal weir for receiving the downflow apron of the tray deck next thereabove; the improvement comprising each tray deck having a plurality of spaced apertures that are spaced between the overflow weir and the seal weir of such tray deck, a bubble cap assembly associated with each aperture comprising an upstanding chimney secured to the tray deck about the aperture, with the upper end of the chimney constituting a valve seat and being at least as high as the top of the overflow weir, a plate valve resting on the valve seat, said plate valve being provided with guide means for positioning the plate valve over the chimney and also for guiding free vertical movement of the plate valve between a position resting on the valve seat and a position spaced thereabove, said guide means comprising a spider comprised of a plurality of angularly spaced, centrally connected, radially and horizontally extending vanes spaced above the chimney, each of said vanes having a downturned end portion that is secured to the chimney adjacent to the upper end of the latter, said downturned end portions of the spider vanes being horizontally spaced from the plate valve to allow a limited horizontal freedom of movement for the plate valve, and a bubble cap carried by and removably secured to the spider having sides extending to a. position below the top of the outlet weir, said sides of said bubble cap having openings therein, said openings being positioned circumferentially around said bubble cap at a height lower than the upper end of said chimney, and means for further equalizing vapor flow through the bubble cap assemblies comprising varying the Weights of said plate valves with the plate valves nearest the overflow weir being relatively heavier than those nearest the seal weir.

References Cited in the file of this patent UNITED STATES PATENTS 8 Hendrix Feb. 3, 1953 Nutter Nov. 10, 1953 Young et al. June 7, 1955 Huggins et al Nov. 27, 1956 Huggins et al. Jan. 7, 1958 Clark et al. Dec. 22, 1959 FOREIGN PATENTS Germany June 6, 1928 Germany Feb. 23, 1938 

